Devices and methods for detecting various gaseous elements are well known in the art. Devices and methods for ventilating occupied spaces are equally well known. For example, U.S. Pat. No. 4,164,172 illustrates a method and apparatus for ventilating an occupied space. The method and apparatus controls the amount of outside air introduced into a given space being ventilated as a function of the oxygen content of the air in the space to minimize the energy expended in heating or cooling air flowing through the space while maintaining the oxygen content of the air above that required for well-being of humans occupying the space. A fuel cell produces an electric current the magnitude of which is a function of the partial pressure of the oxygen present in the air surrounding the fuel cell. The output of the fuel cell is applied to a control circuit of a damper motor to admit outside air when the partial pressure of the oxygen in the occupied space falls to a predetermined minimum level and to exclude outside air and to recirculate return air when the partial pressure of the oxygen in the space rises to a certain maximum level. U.S. Pat. No. 4,478,048 shows an air sensing control system for air conditioners. A unitary air conditioner unit is adapted to be mounted through a wall opening of an enclosure to be conditioned including an air sensing system operative for generating a signal dependent on the level of gases in the enclosure air. The control is operable for adding outside air to the circulating enclosure air or for exhausting enclosure air when a first level of gases sensed and for causing an alarm to sound when the level of gases is above a predetermined value. U.S. Pat. No. 5,120,271 defines a ventilating arrangement for a car. The ventilating system includes an exhaust fan, a carbon monoxide detector, and tubes for evacuating air from the interior of the car if carbon monoxide is present in it. The system can be provided also with a manual fan-operating switch, and formed as a unit which is easily mountable in a car. U.S. Pat. No. 5,267,897 discloses a method and apparatus for ventilation measurement via carbon dioxide concentration balance. The apparatus and method indirectly determines the amount of outside air introduced into the ventilation system of a structure. Carbon dioxide concentrations are measured for return air, outside air and mixed air. The flow rate of mixed air is measured. The volume of outside air introduced into the system is determined without directly measuring the volume of flow rate of the outside air. For calibrating the apparatus, a return air sensor is calibrated to the outside air and a mixed air sensor is calibrated to the outside air or the return air to eliminate inaccuracy due to sensor drift. U.S. Pat. No. 5,292,280 portrays a method and apparatus for controlling ventilation rates and indoor air quality in an HVAC system. The apparatus and method indirectly determines the amount of outside air introduced into the ventilation system of a structure to control the indoor air quality in the structure. Test gas concentrations, preferably carbon dioxide concentrations, are measured for return air, outside air, and mixed (supply) air. The flow rate of mixed air is measured. The volume of outside air introduce into the system is determined through use of the test gas concentration measurements without directly measuring the volume or flow rate of outside air. Preferably, a single sensor is utilized to measure each of the trace gas concentrations in the return air, outside air and supply air, and the various measurements sequentially multiplexed to a controller. U.S. Pat. No. 5,331,310 comprises an amperometric carbon monoxide sensor module for residential alarms. A relatively inexpensive modular component can be substituted for, or used in conjunction with, and existing smoke detector in a commercially available residential fire-detection alarm. The invention comprises an amperometric sensor for carbon monoxide, and a simple current-to-voltage converter circuit that converts the current signals from the sensing electrode into amplified voltage signals. An alarm fitted with this module provides early warning of hazardous conditions, such as a smoldering fire, a leaky furnace, or an otherwise heavily polluted atmosphere. U.S. Pat. No. 5,379,026 consists of a carbon-monoxide detector and alarm circuit for alerting occupants of a structure to a presence of a toxic gas. The apparatus utilizes a probe to detect carbon-monoxide within an air duct of a conventional furnace installation. A siren and a flashing red light are both activated upon a detection of a predetermined amount of carbon monoxide within the air duct, thereby alerting the occupant to the presence of such carbon-monoxide. U.S. Pat. No. 5,576,739 describes a carbon monoxide safety system. The system measures noxious gas concentration in an affected space and for controlling the device producing the noxious gas for decreasing the concentration of the as in the affected space. The invention is particularly described in relation to measuring carbon monoxide concentration in an automobile garage and for controlling the garage door opener circuit to open the garage door in response to a preselected concentration of carbon monoxide. Also, described in particular is a system for deactivating a furnace operating circuit to turn off the furnace in the event of excessive carbon monoxide concentrations. U.S. Pat. No. 5,694,118 includes a gas detection and alarm system for monitoring gas such as carbon monoxide in the atmosphere which can be harmful to humans. The invention has a gas detection/alarm device comprising a detection circuit which detects a predetermined dose of a gas such as carbon monoxide, an indication circuit which visually and audibly indicates the dose detection to the user based on the detection circuit, a microprocessor for digitally operating the detection circuit and the indication circuit, a power conversion circuit which converts AC power to DC power without using any transformers and which supplies the converted constant power to the detection circuit, indication circuit and microprocessor, and a housing which compactly houses all of the components.